Improvement in stove-grates for admitting air to sides and body of the fuel



vBEMAM|N FRANKLIN.

Stove Grate for Admitting Air to `Sides and Body of the Fuel; Y y

No. 125,040. Patented Marql126,1's72,

UNITED STATES y PATENT i ora-ICE.

BENJAMIN FRANKLIN, OF INDIANAPOLIS, INDIANA.

IMPROVEMENTIN sTovveGRATEs For: ADMITTING AIR To slots AND Bonv or lTHE FUI-2L.f

Specification forming part of Letters Patent No. 125,040, dated March 26, 1872.

SPECIFICATION. i

I, BENJAMIN FRANKLIN, of Indianapolis, in the county of Marion and State of Indiana,

`have invented an improved apparatus for preventing smoke in stoves or furnaces of yall descriptions by consuming the particles escaping unconsumed from the incandescent fuel in the fire-pot or chamber thereof, of which the following is a specification:

My invention relates to the supply of currents of warm or hot air to the gases and to the unconsumed particles which may escape from burning fuel while said gases and particles are still in such a heated state as to readily ame and burn in the presence of a proper supply of oxygen, and beforethey have so cooled or condensed as to form smoke and become diiicult of ignition without being again subjected to a very intense degree of heat; it being an established fact that smoke once formed requires nearly twice as much heat to make it flame as it does at the instant immediately preceding` its formation. Again, all

existing methods in obtaining great volumes and long runs of fiame incur a wasteful eX- penditure of fuel; coals, for example, are often melted into clinker and ruined, because the supporter of combustion has not been supplied to the materials of combustion in due proportion, of proper temperature, and at the right time and place. My invention seeks to avoid these evils and attain the most desirable results by the constructions and methods and combinations, as hereinafter described. In other words, my invention relates to improved devices constructed and arranged so as to deliver pure warmair into a furnace in proper division, and at the proper time and place, to prevent the formation of s1noke,in the stead of admitting the air into a column of smoke already formed, as has been heretofore done.

In carrying out my invention, practically, I first lead a channel from the outer air to the base of a hollow space or chamber' constructed with sides or circumference either parallel or ila-ring, and placed within the tire-chamber of a stove or furnace, in the midst of'the fuel therein, and whichIterm an injector. When made tlarin g thesmaller end of this injector isA placed downward;` otherwise, or if made in best form for these orifices. The cap on top of the injector should be usually' lower than the upper edge of the fire-pot or chamber, and

just high enough to be always above the level of the fuel. The air coming in through the channel and rising in the injector will blow out into the fuel and just above it, so asto meet the lighter products of combustion at the instant they are set free, when the air from below through the fuel has lost all or most of its oxygen. vAt that -instant they will most readily inflame. An instant after smoke would be formed and the difficulty ofiniiaming would, in rapid combustion, be nearly doubled, and in slow combustion made economically im prac ticable. may multiply injectors to any extent in proportion to the area of the fuelsurface, and may place them in any situation, feeding them with air through one or more channels. I may also place valves or registers in or at the mouth of the channel or channels, so as to control, at will, the amount, speed, or force of the current of air passing into the injectors In combination with this injector, or independently thereof, I also form a hollow air-space or chamber within or without the sides or walls of the tire-chamber of the stove or furnace, either to surround the same `wholly or to embrace only a portion thereof, which said chamber shall be provided with outer openings for the admission of fresh air at points thereof remote from the point at which the fuel in the fire-chamber flames. This air-space will prevent contact of the outer air of a room with overheated iron, and thus avoid the vi tiation of the atmosphere to be breathed. 4At or near the upper edge' of this air-chamber .I open a narrow horizontal-space or slit to communicatewith the firechambeiy andalso ing devices.

numerous vertical orifices, which, starting below the rim or top of' the fire-pot or chamber, extend down below the full level therein, so as to deliver heated air from the air-chamber to the outside or circumference of the mass of fuel or materials lof combustion, essentially as a-bove describedin the case of the injector. I may vpartition off this jacket or air-chamber so as to feed it from many points and deliver air from more than one space. My invention consists, further, in combining these two methods of injecting air into a fire-chamber, by which they mutually aid each other in mingling the supporter with the materials of' combustion, and thus secure the most complete and economical results without impedin g the draught or blasts. The air-supplying channels of either the injector or air-jacket may be connected with a blast mechanically produced, and the invention thus adapted to metallurgie or steamgenerating furnaces and to open gra-tes. By thus combining the admission of air to the circumference of' the mass of the fuel and to its upper surface with the ordinary draught or blast of air from below, through the mass of the fuel, I am enabled, by properly regulating and controlling the feeding ot air both belowr and above, to effect the utmost economy of' fuel. By this mea-ns, also, the waste or injury caused by a melting of the fuel and by the formation of clinker would-be very much lessened or entirely prevented.

- In the accompanying drawing I have illustrated the application of my invention to a heating-furnace. Figure l is afront elevation of the furnace; Fig. 2, a central vertical section in the lille .fr :v of Fig. l, illustrating the application of a jacket and injector to thefurnace forthe purpose of produ cin gsmokepreventive flame-dra-ughts; and Fig. 3 is a horizontal section in the line y y of' Fig. 2.

A is lthe fire-pot; B, the gra-te; 0, the ashpit; and D, the upper radiating-chamber of a stove or furnace of any approved' form. E is the facing-plate; F, the fuel-door; G, the feeding-spout; and H, the ash-pit door ot' a furnace fitted with my improved smoke-prevent- The fire-pot may be made ilaring, as shown in Fig. 2, and surrounded by a cylindrical jacket, K, to form a concentric airchamber, W, gradually contracting toward the top, so that as the air passes upward through it the current will be drawn through a narrower space, and consequently brought into closer and more direct contact with the wall of the lire-pot. In 'some cases it may be well to make the fire-pot perpendicular or even wider at the bottom than the top, the jacket remaining cylindrical. A narrow aperture or slit, s, indicated by black lines in the drawing, is formed in the wall of the fire-pot or chamber, over the top of' the fuel when at its proper level, so as to permit the air heated within the chamber W (formed by the jacket K) to flow in a thin sheet into the fire-pot directly over the fuel, for the purpose hereinbefore explained; and, for use `in combination therewith, narrow apertures or slits r r are formed to extend vertically from or near the upper slit s, so as to reach nearly to the grate.

L is an air-channel, extending from the faccplace of the furnace to the concentric chamber W to supply air to said chamber. The mouth of' said channel is covered by aregister, M, to control the admission of air thereto. To producea more uniform supply and-diffusion of air around the fire-pot I contemplate a division of' the air-chamber formed by the jacket K int-0 two or more compartments by means of vertical partitions n n, as shown in Fig. 3, in which case each compartment is supplied with air by an independent opening, controlled by a separate register, although all the registers may, if desired, be so connected as to operate simultaneously' by a movement of one of them. In large furnaces, where rapid combustion is required, the air-chambers should be less contracted than in the case of stoves and heatingfurnaces; but in all cases the orifices through which the air is discharged into or over the fuel must be small in area and closely approximated, so that the injected air shall mingle thoroughly and readily with the particles to be consumed. Instead ot making the `airchamber concentric, to inclose the lire-pot as illustrated, it may be formed at one side or at one end only ofthe fire-box. P represents an air-chamber formed within the fire-pot ofthe furnace, so as to be partially surrounded by the fuel placed therein, (as shown in Fig. 3,) and which I have termed the injector. This chamber may be circular and sloping, or naring from bottom to top, so as to be'wedged or pyramidieal in shape, as illustra-ted in Fig. 2. Its upper end is placed just above the highest level to which the fuel should be placed in the furnace, and its lower end, extending downv ward nearly to or below the grate, communicates with the outer air through a tube or channel, Q, which, for the sake 'of convenience, is carried forward under the air-channel L ot' the jacket, so as to be opened and closed by the same register M. Y Its sides are provided with a series of' narrow slits or apertures (indicated by black lines in the drawing) extending nearly to its lower end, and its top is covered by a cap-plate, which preferably is made to project over its sides. Under this cap-plate isleft a horizontal open space, through which the air heated within is projected into the fire-space over the fuel in opposition to the currents of air injected from the air-chamber about the wall ofthe lire-box, to produce thereby a more complete intermingling ot' the warm fresh air with the incandescent particles escaping from the burning fuel under the operation of the draught passing up through the same.

I contemplate using in larger furnaces two or more of' theseinteriorair-chambers or injectors, either alone or in combina-tion with one or more exterior air-chambers, as shown inthe drawing. I construct these injectors usually ot iron, in sections or otherwise, so that they can be readily and cheaply renewed. In-some cases, asin blast-furnaces, or others, where the central heat is very great, I construct. them of brick or stone, or any other suitable material, but always so that great defects can be readily and cheaply repaired. They will bear, however, a great amount of heat without injury, because even holes would not impair their usefulness. In certain cases, however, I might protect them `in a manner analogous to that used with the tuyeres of blast furnaces. I provide against the falling of dust and small particles of-coal into the injector not only by the shape thereof, and by the cap, as above described, but when burning dust or slack I further provide against that great evil by suitable cap-1.)lates placed over the slits not only ofthe injector, but also in the sides ofthe firepot. I prefer that the air-supply channels or chambers shall'in no case open into or communicate with the ash-pit, as dust and ashes will in such cases inevitably rise and choke more or less the small orifices by which air must be fed to the tire, an evil that may de stroy the whole use and value of the injector and air-jacket, inasmuch as the oriices must be small and numerous in order to effect that prompt and complete lninglin gof the supporter 7 with the materials ofcombustion, upon which the success in utilizing those materials with the greatest ease and economy absolutely depends. By means of my arrangements of air-channels I not only supply thoroughly oxygenated air, but keep my feeding air clean, and thus avoid all danger of choking or impeding the smallest orifices 5 and further, by blowing in clean air in a heated condition, I cause the particles of dust of coal to mass together, and thus make them too large to choke or impede the iiow of air through said orifices. The horizontal space under the cap of the injector induces the air to strike the cap, and thereby partly protects it against the eifects of excessive heat; it also allows the throwing in of a ring of air to meet and inclose the jets of combustion effected by means of the orifices below, thus gathering up any stray portions and promoting that outward flow, which makes the injector also valuable in combination with the feeding of air to the circumference of the fuel from thejacket. In locomotive and other boiler furnaces, in metallurgie glass furnaces and the like, I lead channels for air along the sides, ends, and sometimes roof, to communicate with the air-delivery jackets or chambers, or with the injectors, always delivering the air, as herein described, at the point where the air from below through the fuel begins to be exhausted and the smoke is just ready to form; or the air-chambers may be so divided as to form return iiues, in which the current will pass back and forth over the heated surfa ce in its course toward the draught openings, and thus be very highly heated before its injection upon the fuel. The division of the iiame-draughts through the numerous apertures of the air-chambers prevents ablast at any one pointsufticient to blow or carry away the ignited particles unc'onsumed, which would be especially the case were the mass of fuel at a comparatively low temperature. In this my invention theformation of vaporous pyroligneous acid, which, when once formed, deadens combustion, is prevented, and its constituents consumed before they unite.

I claim as my inventionl. A series of narrow air-delivery slits or apertures formed in the walls or sides ofthe tire-pot or chamber of a stove or furnace, to extend from a point at or below the lowest level to which the burning fuel will in proper practice be allowed to fall, to a point at or above its highest practical level, and communicating with one or more air-supplying spaces formed about the tire-pot or chamber, and combined with one or more horizontal aindeli'very apertures formed in or over the upper edge of the fire-pot or chamber, substantially as and for the purpose herein setforth.

2. In combination with the subject-matter of the foregoing claim7 one or more injectors 7 or hollow chambers constructed with parallel or upwardly outwardly-haring sides, and pierced with a series of up-and-down narrow slits or perforations in the sides thereof, and wit-l1 one or more narrow horizontal slits or apertures over or in the top edge thereof, combined with one or more air-feeding channels, and placed within the fire-pot of a stove or the tire-chamber of a furnace, substantially as and for the purpose herein set forth.

BENJAMIN FRANKLIN.

Iiitnesses:

DAVID A. BURR, F. H. BURR. 

